refactor: strip <rootDir> from collectCoverageFrom values (#5524)

* refactor: strip <rootDir> from collectCoverageFrom values

All values given to collectCoverageFrom are relative to the root directory,
so usage of <rootDir> results in invalid file paths.
With these changes, <rootDir> will be silently replaced.

ISSUES CLOSED: #5499

* chore: ignore JetBrains configuration files

* refactor: wrap mapping in a nullcheck

* Update .gitignore

CHANGELOG.md

@@ -9,6 +9,10 @@
 * `[docs]` Add documentation for interactive snapshot mode ([#5291](https://github.com/facebook/jest/pull/5291))
 * `[jest-editor-support]` Add watchAll flag ([#5523](https://github.com/facebook/jest/pull/5523))
 
+### Chore & Maintenance
+
+* `[jest-config]` Allow `<rootDir>` to be used with `collectCoverageFrom` ([#5524](https://github.com/facebook/jest/pull/5524))
+
 ## jest 22.2.2
 
 ### Fixes

packages/jest-config/src/__tests__/normalize.test.js

@@ -186,6 +186,31 @@ describe('collectCoverageOnlyFrom', () => {
   });
 });
 
+describe('collectCoverageFrom', () => {
+  it('substitutes <rootDir> tokens', () => {
+    const barBaz = 'bar/baz';
+    const quxQuux = 'qux/quux/';
+    const notQuxQuux = `!${quxQuux}`;
+
+    const {options} = normalize(
+      {
+        collectCoverageFrom: [
+          barBaz,
+          notQuxQuux,
+          `<rootDir>/${barBaz}`,
+          `!<rootDir>/${quxQuux}`,
+        ],
+        rootDir: '/root/path/foo/',
+      },
+      {},
+    );
+
+    const expected = [barBaz, notQuxQuux, barBaz, notQuxQuux];
+
+    expect(options.collectCoverageFrom).toEqual(expected);
+  });
+});
+
 function testPathArray(key) {
   it('normalizes all paths relative to rootDir', () => {
     const {options} = normalize(

packages/jest-config/src/normalize.js

@@ -160,6 +160,12 @@ const normalizeCollectCoverageFrom = (options: InitialOptions, key: string) => {
     value = options[key];
   }
 
+  if (value) {
+    value = value.map(filePath => {
+      return filePath.replace(/^(!?)(<rootDir>\/)(.*)/, '$1$3');
+    });
+  }
+
   return value;
 };